Unlike several previous Heisei Rider Series, no alternate name has been given yet for the three O's in the title (Ｗ（ダブル） read as "Double" and 555（ファイズ） read as "Φ's/Phi's/Faiz") aside from an alternate spelling of the name of the main Kamen Rider: Ooz.[2] Both "OOO" and "Ooz" are intended to be read as "O's", referring to the multiple uses of the letter O in the title as well as "multiple kings" (王ｓ,Ōzu?). The title OOO signifies the three medals that the main Kamen Rider uses to transform as well as being representative of the infinity symbol () with an additional circle.

Eiji Hino is a traveling man who has no place to call home and a tragic past. When metallic creatures known as the Greeed awaken after their 800-year slumber to attack humans and feed off of their desires, the disembodied arm of the Greed named Ankh gives Eiji a belt and three Medals to fight the other Greed as Kamen Rider OOO. The mysterious Kougami Foundation approaches Eiji and begins assisting him in his fight against the Greed, though their true motives are not clear. As Eiji fights the Greed and their Yummy monsters, learning more of the Greed and Ankh, he starts to find a purpose beyond his journey.[1]

OOO, Den-O, All Riders: Let's Go Kamen Riders(オーズ・電王・オールライダー レッツゴー仮面ライダー,Ōzu Den'ō Ōru Raidā: Rettsu Gō Kamen Raidā?),[5] released on April 1, 2011, commemorates the 40th anniversary of the Kamen Rider Series featuring the cast and characters of Kamen Rider Den-O, Kamen Rider OOO, and other characters from the past franchise series.[6] The event of the movie take place between episode 26 and 27

Kamen Rider OOO Wonderful the Movie: The Shogun and the 21 Core Medals(劇場版 仮面ライダーオーズ WONDERFUL 将軍と２１のコアメダル,Gekijōban Kamen Raidā Ōzu Wandāfuru: Shōgun to Nijū-ichi no Koa Medaru?)[7] is the main theatrical release for Kamen Rider OOO, released on August 6, 2011, alongside the film for Kaizoku Sentai Gokaiger.[8] It also features the first on-screen appearance of the 13th Heisei Kamen Rider: Kamen Rider Fourze.

A port of Kamen Rider: Climax Heroes titled Kamen Rider: Climax Heroes OOO(仮面ライダー クライマックスヒーローズ オーズ,Kamen Raidā Kuraimakkusu Hīrōzu Ōzu?) was released on both the PlayStation Portable and Nintendo Wii on December 2, 2010. In addition to adding Kamen Rider OOO to the game, the previous Heisei Riders' most powerful forms (e.g., Kuuga Ultimate Form & Double CycloneJokerXtreme) are added as playable characters as well as other Heisei Kamen Riders not included in either of the two previous versions.[13][14]

Kamen Rider OOO Hyper Battle DVD: Quiz, Dance, and Takagarooba!?(仮面ライダーオーズ ハイパーバトルＤＶＤ クイズとダンスとタカガルバ,Kamen Raidā Ōzu Haipā Batoru Dī Bui Dī Kuizu to Dansu to Takagaruba?) was released alongside an issue of Televi-Kun magazine. The DVD featured the Kangaroo Medal, which was used by Kamen Rider OOO to transform either his arms or legs to have kangaroo-themed powers.

"Kangaroo Dance" is a song used in the Hyper Battle DVD featuring Akira Kushida chanting "Kangaroo" in the background with composition & arrangement from Shuhei Naruse.

Kamen Rider OOO: Final Episode(仮面ライダーオーズ FINAL EPISODE,Kamen Raidā Ōzu: Fainaru Episōdo?) is the director's cut version of the last two episodes of Kamen Rider OOO put together. It was released to DVD and Blu-ray on February 21, 2012.

Kamen Rider OOO(仮面ライダーオーズ,Kamen Raidā Ōzu?), written by Nobuhiro Mori, is part of a series of spin-off novel adaptions of the Hesei Era Kamen Riders. The novel is split in three parts. The first part, Ankh's part, focuses the origin of the Core Medals, the King, and the Greeeds from Ankh's point of view and reveal secrets inanswered from the series. The second part, Birth's part, takes on the Birth Driver's point of view, deciding between Akira Date and Shintaro Goto to see who is worthy to use it. The final part, Eiji's part, focuses on Eiji's past and reveals how he met Alfreed. The novel was released on November 30, 2012.

"Anything Goes!" was released on November 17, 2010, as a standard CD and a CD+DVD combo pack.[19] The rapping on the song was performed by Rah-D, who provides his vocal talent in some of the show's background music.[23]

A balladic version of the song titled "Anything Goes! Ballad" was during the finale of Kamen Rider OOO. Ohguro stated that she thought that the song would also work as a slow ballad, especially after she has been watching how the series has progressed, and recorded the song during her hiatus from releases. The balladic version was released as a single on December 7, 2011.[24]

Ending themes

Each of the series' various ending themes are titled in such a way to resemble the Kamen Rider OOO Combo that they serve as the theme for. The songs also feature Akira Kushida, the voice for the OOO Driver, chanting the name of the combo throughout the song. Ayano, a session guitarist for many of the recent Kamen Rider Series songs and member of the "Tsuyoshi & Ayano" group from the Kamen Rider W radio show, performs guitars on all of the tracks.

"Regret nothing ~Tighten Up~" was recorded throughout late September 2010 and recording completed on October 2, 2010. Shuhei Naruse is the song's producer and it is sung by Shu Watanabe under the name of his character Eiji Hino.[25] It was first used in the October 3, 2010, episode.[26] The pronunciation of "Tighten Up" is intended to mimic the pronunciation of "Tatoba". When played during scenes with other Combos, the "Tatoba" chant is removed from the song.[27] The single for "Regret nothing ~Tighten Up~" features a ska arrangement by trombone player Eijiro Nakagawa.

"Got to keep it real"

Lyrics: Shoko Fujibayashi

Composition & Arrangement: Shuhei Naruse

Artist: Eiji Hino (Shu Watanabe)

Episodes: 6, 16, Movie War Core

The title of "Got to keep it real", Gatakiriba Combo's theme song, was revealed on Shu Watanabe's official blog on Gree.jp.[28] The chorus features Sunaho of Labor Day. The single for "Got to keep it real" features a trance arrangement by Yoichi Sakai.

"Ride on Right time"

Lyrics: Shoko Fujibayashi

Composition & Arrangement: Shuhei Naruse

Artist: Eiji Hino (Shu Watanabe)

Episodes: 9, 10, 15, 40, 42, 45

"Ride on Right time" is Latorartar Combo's theme song. The additional rap vocals are by Tsuyoshi Himura, the Tsuyoshi of "Tsuyoshi & Ayano". The single for "Ride on Right time" features a "mixture" arrangement by Shamo and Florida Keys member Junichi "Igao" Igarashi.

On January 12, 2011, Shu Watanabe announced on his Gree blog that he was recording a new song for OOO, specifically for the "red bird guy" (赤い鳥のヤツ,akai tori no yatsu?).[29] The song has since been revealed to be titled "Time judged all", the theme for Tajadol Combo, and is a duet with Ryosuke Miura as Ankh.[30] The song features Hyuga Rei and Mami Yanagi performing in the chorus, chanting in German. The "Full Combo Collection" album features a "dialogue" version as a bonus track.[31]

"Shout out"

Lyrics: Shoko Fujibayashi

Composition & Arrangement: Shuhei Naruse

Artist: Eiji Hino (Shu Watanabe)

"Shout out" was first announced on April 17, 2011, by DJ HURRY KENN on the OOO Internet radio show, where he said the song for Shauta Combo would have a "Double-Action Rod form"-like feel, The song was played on the radio show, however it was never played in the series.[32] Kaori Nagura of Kamen Rider Girls joins in the chorus.

Tsuyoshi and Ayano of the Kamen Rider W Internet show Head Wind: One-Game Match!! have a cameo appearance as street musicians, Michibata Lion (路端ライオン,Michibata Raion?), in episode 35 where they perform their radio show's theme song "WIND WAVE".

The first soundtrack for Kamen Rider OOO was released on November 17, 2010; it includes an edit of the series' opening theme "Anything Goes!". The second soundtrack was released on June 22, 2011. The Kamen Rider OOO: Full Combo Collection album was released on July 27, 2011, debuting at number 8 on its day of release on Oricon's daily album ranking.

DJ HURRY KENN announced on Twitter that Kamen Rider OOO‍ '​s "final song" will be recorded on July 18, 2011.[33]

^This episode was originally scheduled to air on March 13, 2011, but TV Asahi postponed the airing of this and several other television programs to air news coverage on the Tōhoku earthquake and tsunami.

^This episode was the final Kamen Rider episode to air on analog television in most of Japan. Analog television broadcasts ceased at noon that day.